bio set 4 (2).txt
Card Set Information
bio set 4 (2).txt
bio set 4
# Why are integral proteins embedded into membranes?
Because they have alot of hydrophobice amino acid side chains. Membranes are hydrophobic by nature.
# How can you get an intergral membrane protein out of the membrane?
By adding a ionic detergent, it will "wash" the protein out of the membrane so it can be viewed independently.
# Which detergent will get a membrane protein out of the membrane? a nonionic or a ionic?
# What detergent are we going to use?
ionic detergent = SDS
# What are we assuming the SDS-PAGES's charge is in this class?
# What is the point of ripping a membrane protein out of a membrane?
To get in solubilized in the water
# What is the starting material for membrane proteins
# What are the only membrane that mature RBCs have?
# Why were the RBCs looked at first?
Because they only consists of a plasma membrane and nothign else (no ers, golgi, etc.)
# How do you get to study the plasma membrane of an RBC and nothign else?
By "popping" it and getting the "ghost"
# How do you get the RBC "ghosts?"
Hemolysis (pop and reseal after osmotic shock)
# The hemolysis of a RBC is hypotonic or hypertonic?
# How do you physically just get the ghosts of the RBC?
Preform hemolysis on the RBCs, centrifuge it, then throw out the supernatant (goo inside), to leave the "ghosts"- plasma membrane
# RBC ghosts are _____ plasma membranes
# If you want to know what pure plasma membrane are you need to study the ...
# If you add SDS-PAGE to the RBC ghosts what will it do to them?
rip the membrane proteins out of the membrane, and cover them in detergent
# "top of the gel" means
Where we started the experiment
# When SDS-PAGE is added to a membrane, what proteins come off? Peripheral or integral?
Both of them, peripheals are easily washed away and integrals are ripped out by the detergent.
# what is your first assumption about membrane proteins?
That they are all negatively charged and all soluble.
# How do you start the electrophoresis?
By turning on the electricity and having the proteins pull towards the positive pole (because proteins *are negative* opposites attract)
# How do we know when to turn off the electricity for the electrophoresis?
When the proteins hit the colored dye at the "bottom"
# How would you determine which proteins are peripheal and which are integral in gel electrophoresis?
Cetrifuge the RBC ghosts in a high salt solution. then re-do the gel electrophoresis. Peripheal proteins will have come off due to the high salt, and all that is left is the intergral proteins.
# How would you know what the molecular weight of certian proteins are?
By indicating bands with known molecular weights.
# You can identify a protein by its...
# With SDS coating proteins, they move by ___________ towards the _________ pole.
# The smaller proteins move ________ in electrophoresis
# What is electrophoresis used for?
Which proteins are integral and which are peripheral.
# What is Actin?
* A long fibrous protein
* peripheal protein
* CytoSkeleton like
* Ties together integral protiens
* (cytoskeletal filaments)
# Sugars are on the...
outside of the cell
# You will only see what three things facing the outside of the cell?
# All cytofilaments are ....
polymers of proteins
# Cytofilaments are assembled from a pool of protein subunits and ___________.
# Each protein is a polymer of...
# Polymerize proteins to make a....
# Filament means...
a polymer of proteins
# Protein subunits start as monomers and are polymerized to....
# protein filaments are depolymerizied into
# If a cell wants to divide what must they do to the cytofilaments?
# Some filaments are _________, always changing by assembly and disassembly
# If filaments grow more than they shrink they get ....
# If filaments shrink more than they grow they get...
# What are the three main kinds of cytoskeletal filaments?
* intermediate filaments
# What is the typical diameter size of a microtubules?
# What is the typical diameter size of a intermediate filaments?
# What is the typical diameter size of a microfilaments?
# How can you theorectially tell which cytoskeltal filament is which?
By cutting them and measuring the diameter of it.
# What are microtubules?
* A "tube of tubulin"
* Tubulin subunits are dimers (heterodimers)
* heterodimers made of Alpha tubulin and Beta tubulin
# In a microtubules, aplha and beta tubulins _________ to make the dimers.
# Do you need atp for alpha and beta tubulins to spontaneously form micrtobules in vitro?
# what is the main idea behind intermediate filaments?
that you can put many of them together and just end up with one big intermediate filaments
# Microfilaments are made of..
# What does Micofilaments, actin filaments, f-actin and filamentous actin have in common?
they are all the same thing
# Actin monomers are...
# if you put actin monomers together by polymerization you get...
# How do filaments become stronger?
By turning into a double helix of filaments
# When we say microfilaments is really means the...
double helix of filaments
# Globular actin is not just a glob because
it has structure to it
# ATP is required to make what kind of filaments?
# GTP is required to make what kind of filaments?
# "various globular proteins" are needed to make what kind of filament?
# What End are microtubules built on?
The "+" end
# Where are intermediate filaments built on?
internal (all over the place)
# What end do microfilaments grow on?
the "+" end
# Do microtubules have polarity?
# Do intermeidate filaments have polarity?
# do microfilaments have polarity?
# What does a GTPase do?
breaks down GTP
# What does a ATPase do?
breaks down ATP
# What is the enzymatic activity of microtubules?
# what is the enzymatic activity of intermediate filaments?
# what is the enzymatic activity for microfilaments?
# What are microtubules motor proteins?
# what are microtubules motor proteins?
# what are intermeidate filaments motor proteins?
they have none
# What are the microtubules major group of associated proteins?
# What are the major group of associated proteins for microfilaments?
# What is the structure of microtubules?
Stiff, hollow tube
# What is the structure of intermediate filaments?
tough, ropelike fibers
# What is the structure of microfilaments?
flexible, helical filament
# Who has microtubules?
# Who has intermediate fibers?
# who has microfilaments?
# What is the primary function of microtubules?
* MAINLY intracellular transport
* Cell Organization
# What is the primary function of intermediate filaments?
# What is the primary fuction of microfilaments?
# The molecular weights of intermediate fibers are usually...
all over the place
# What would pure microtubules look like on SDS-PAGE w/high salt?
two seperate bands (alpha and beta tubulin)
# what is the genral molecular weight of the tubulins in pure microtubulins on SDS-PAGE?
about 66 kDa
# What would microfilaments look like on SDS-PAGE w/high salt?
One band of actin
# What is the general molecular weight of the actin in microfilaments on SDS-PAGE?
about 43 kDa
# SDS breaks down everything into it's __________ form.
# How do you use SDS-PAGE to identify a protein?
It's size againt the molecular standards
# How can you stop cell division?
Stop microtubules from growing
# Microtubules are repeating units of ....
heterodimers (alpha and beta)
# what is the tubulin dimer?
The subunit for the protofilament
# What is a protofilament?
One line of tubulin
# Protofilaments form...
# Tubulin dimers, microtubules are _________, no need to add energy.
spontaneous, they form on their own.
# In microtubules, alpha is on the _______ end.
# in microtubules, beta is on the ________ end.
# Microtubles always grow at the ______ end.
# Does GTP hydrolysis is microtubles provide energy?
# The complete formation of a microtubule is?
* The alpha and beta forms a tubulin dimer
* The tubulin dimer forms a protofilament
* 13 protofilaments form a microtubule
# Microtubule is ...
A clynider made of 13 protofilaments side by side (cytoplasmic)
# If you preform a cross section on a microtubule how many protofilaments would you see?
# Is GTP hydrolysis necessary for the Microtubule to grow?
# Colchicine inhibits _________.
# what is the role of GTP in microtubule assembly?
To allow protofilaments to grow
# What are the three binding site on the beta of a tubulin dimer?
* Ca ++ binding site
*Colchine Binding Site
* Exchangeable GTP Binding Site
# You cannot add to a protofilament unless the beta in the last tubulin dimer has..
# Charged tubulin is?
Tubublin that is GTP bound.